2. To make a buffer at pH = 10.83, which of the following should be mixed?
   
   
   1. One-half equivalent of NaOH with one equivalent of H₂CO₃.
   2. One and one-half equivalents of NaOH with one equivalent of H₂CO₃.
   3. One and one-half equivalents of NaOH with one equivalent of H₃PO₄.
   4. Two and one-half equivalents of NaOH with one equivalent of H₃PO₄.